Pneumatic-despatch-tube apparatus.



J. T. COWLEY.

PNEUMATIC DESPATOH TUBE APPARATUS.

V APPLICATION FILED NOV. 28, 1906. 1,102, 185.' Patented June 30,1914,

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J. T. COWLEY. PNEUMATIC) DESPATOH TUBE APPARATUS.

APPLIOATION FILED NOV. 28, 1906.

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l filne J. T. COWLEY.

PNEUMATIC DESPATCH TUBE APPARATUS.

APPLICATION IILED NOV. 2a, 1900.

1, 1 O2, 185, Patented June 30, 1914.

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J. T. COWLEY.

PNEUMATIC DESPATOH TUBE APPARATUS.

APPLICATION IILBD NOV. 28, 1908.

1,1 02, 185. Patented June 30, 1914.

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J. T. COWLEY.

PNEUMATIC DBSPATGH TUBE APPARATUS.

APPLIOATION FILED NOV. 25, 1906.

1,102,185. Patented June 30, 1914.

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J. T. COWLEY.

PNEUMATIC DESPATOH TUBE APPARATUS.

APPLICATION TILED NOV. 28, 1906.

UNTTED STATEfi PATENT OFFICE.

JAMES T. COWLEY, OF BOSTON, MASSACHUSETTS, ASSIGNOR T LAMSON COMPANY, OF NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY.

PNEUMATIC-DESPATCH-TUBE APPARATUS.

Specification of Letters Patent.

Patented June 30, 1914:.

Application filed November 28, 1906. Serial No. 345,464.

To all whom it may concern:

Be it known that I, J AMES T. COWLEY, of Boston, in the county of Suffolk and State of hilassaclmsetts, have invented certain new and useful Improvements in Pneumatic- Despatch-Tube Apparatus, of which the following is a specification.

My invention relates to improvements in pneumatic despatch tube apparatus and particularly to that class wherein a single tube is used for the transmission of carriers there through in either direction.

The object of this invention is to control the operation of the power for producing a current of air in either direction through the transmission tube as required and limiting and controlling the use of power to the interval necessary for the propertransmission and delivery of the carriers. This ob ject is accomplished by utilizing a pneumatically-controlled switch which is adapted to be operated fromeither terminal of said tube to start or stop independently one of two oppositely-acting pressure-producing members or pumps.

in the accompanying drawings which illustrate a construction embodying my invention, Figure 1 is a diagrammatic view of a single-tube pneumatic system showing power connections therewith and mechanism for controlling the same. 2 and 3 are sectional views of the pneumatic pump-controlling mechanism hereinafter described. Fig. 4t is an elevation of the valvecontrolling mechanism regulating the direction of the air current. Fig. 5 is a detail view of the upper end of valve-controllin mechanism shown in Fig. 41-. F 6 is a plan view of one of the two pump controlling switches. Fig. 7 is a detail view of a portion of the switch shown in Fig. 6. Figs. 8 and 9 are enlarged detail views of the auto matie timing device for stopping the pump. Fig. 10 an enlarged view of the pressuredespatching and vacuuiii-receiving terminal of said transmission tube.

Like letters of reference refer to like parts throughout the several views.

Referring to F 1,--A represents a central station and Ba sub-stationconnected by the single transmission tube 1 the tube lis 5 1 wire 37 with the opposite line wire L". The

supported at station B by a standard 2 to which is attached a receptacle 3 adapted to receive the carriers discharged at said station. At the central station A there is connected with the tube 1 a supply pipe 4 and supported by said pipe is a receptacle 5 adapted to receive carriers discharged from the tube at the central station A. At its lower end the supply pipe4is connected by a T with two pipes 6 and 7, the pipe 6 being connected with the exhaust port of a pump 8 and the pipe 7 being connected with the inlet port of a pump 9. Communication between the pipes 4-, 6 and 7 is controlled by two valves 10 and 11. The inlet port of pump 8 is connected by a conduit 12 with a cylinder 13 which is part of the automatic timing mechanism for controlling the period of operation of the pump 8. The pump 8 is connected and driven by a belt with a motor 30.

The cylinder 13 is divided near its middle by a hollow partition 14; with which the conduit 12 communicates and in this partition there is an opening 15 connecting the conduit 12 with the lower part of the cylinder 13, and an opening 16 adapted to connect the conduit 12 with the upper part of the cylinder 13, which communicates with the atmosphere through port 17. Mounted in the lower part of cylinder 13 is a piston 18 whose connected rod 19 carries a valve 20 adapted to control the port 16 and a collar 21 fixed to its upper end and adapted to operate a switch 22 mounted on top said cylinder 13.

The conduit 12 is connected with the lower part of the cylinder 13 below the piston 18 by a by-pass 23 which is regulated by a screw-valve 24; located in this by-pass 23 is a port 25 normally closed to the atmosphere by a valve 26 mounted on an armature lever 27 pivoted at 28 in a bracket projecting from the cylinder 13. A spring 29 connected with said lever 27 normally holds the valve 26 closed. The motor 30 wliichdrives the pump 8 has one terminal connected by a wire 31, switch 32 and wire 33, with a line wire L. The other terminal of said motor is connected by a wire 34. with one of a pair of contacts 35. the other of said contacts being connected by a wire 36, switch 32 and tacts being connected by a wire 46, switch" 42 and wire 47 with the opposite line wire L The contacts are normally disconnected but are adapted to be connected to start motor 40 by a bridge-piece 48 carried by the armature of a magnet 49 when said magnet is energized.

The valves 10 and 11 as shown most clearly in 4, are operated by a member,

pivoted at 51 to the pipe 4. The lower end of member when swung in one direction is adapted to engage an arm 52 fixed to the stem of valve 11 and open said valve, and when swung in the opposite direction, is adapted to engage an arm 53 and open valve 10, and as will be clear, when one valve is opened, the other valve is left in its normal or closed position. The arms 52 and 58 carry weights 54 which return the valves to and hold them in their normal closed positions with the arms 52 and 53 against stops 55. Other stops 56 are also provided to engage the weight 54 and limit the opening movement of each valve to about one-quarter of a revolution. The member 50 is swung to the right in Fig. 4 to open valve 11 by means of a magnet 57, and to the left in said figure to open valve 10 by a hand-operated lever 58 pivoted at 59 which acts through a stem 60 and links 61 to swing the member 50 in that direction. This movement 'of member 50 to the left is actuated by a swinging movement of lever 58 to the rightin Fig. 4 at which time said lever engages a laterally projecting pin 62 on the stem 60, which pin is so placed with relation to lever 58 that when the latter is held in its normal position by a returning spring 63, there is lost motion provided for between pin 62 and lever 58 suflicient to allow the magnet 57 to swing member 50 to the right independently of the lever 58. The lever 58 is located at station A and is controlled by the operator to open valve 10 while the closing of said valve 10 is controlled through the return movement of member 50 by the pressure in the pipe 4. To provide for this, the stem 60 extends through a chamber 64, the latter being con nected at one side of the diaphragm 65 with pipe 4 by a conduit 66. The magnet 57 is controlled by the operator at station E and to provide for this, the circuit 67 of magnet 57 Contains a switch 68 whose movable arm ber. I p spring T3 which iiormally holds the stem 69 is connected with and operated by a movement ofthe stem 70 which extends through a chamber 71 and has fixed to" it a diaphragm 7 2 mounted centrally'in said chamt on s d of diaphra m 2. is a at one extreme of its movement with switch member 69 open. The chamber in the easing 7'1 on the opposite side of the diaphragm 72 is connected by a conduit 74 with another diaphragm chamber 75 within which is a diaphragm 76 mounted at its middle with a stem 77 which in turn is connected with a hand lever 7 8 through which said diaphragm may be operated as a pump to transmit an impulse of air through the conduit 74 to chamber 71, and through means of diaphragm 72 and stem 70, to close switch 68. In this way, the operator at station 13 closes the circuit 67 of magnet 57 which results in the member 50 being swung to the right (Fig; 4) to openthevalve 11.

When the operator at station A operates the lever 58 to open the valve 10, the pump 8 is automatically started and a current of air is established from said pump in the direction indicated by the arrow through pipe 6 and supply pipe 4 and through the transmission tube 1 in the direction indicated by full line arrow, and when magnet 57 is energized by the operator manipulating the lever 78 at sub-station B to open the valve 11, the pump 9 is started creating a current of air through the tube '7 supply pipe 4 and transmission tube 1 in the opposite direction as indicated by the dott-edline arrow (Fig. 1).

In order to rovide for automatically starting one or t e other of the two pumps according to which of the two valves is open, the circuits of the magnets and. 49 are automatically operated and controlled by the member 50 as follows: To the upper end of member 50 is fixed a block 79 of insulating material (Fig. 4) on which is mounted. four spring contact arms 80 ar ranged in two pairs connected by the metal strap or bond 81, so that electrically all the arms 80 are as oneKF'igsQ; 4-5). J ust-above the arms 80 'aretwo pairs of contacts 82 and 83 so arranged that when member 50 is swung to the left to open valve 10, the arms 80 connect the contacts 82, and when swung to the right toop'en the valve 11, the arms 80 connect the contacts 83. The contacts 82 and are fixed to and insulated from the metal blocks 84 mounted on an insulated arm 85 projecting from the pipe 4. The contact-s 82 are electrically connected as shown in Fig; 5 with binding posts 86 by wires 87, while the contacts 83 are connected by wires 88 with binding posts 89; one of the binding posts 86 is connected by a wire 90 with one end of the coil of magnet 39. The other end of the coil of said mag net is connected. by a wire 91 with one of the two contacts 92 of switch 22, while the other contact 92 is connected by wire 93 through a battery and to the other binding post 86. The other binding posts 89 are connected by wires 9-il and 95 with a battery and the ends of the coil of the magnet 1$). It will thus be clear that the member 50 when swung in one direction by means of lever 58 to open valve 10 will close the contacts 82 by means of arms 80, thereby energizing the magnet 39 and that also, when the member 50 is swin'lg in the opposite direction by operating the lever 78 to open the valve 11, the arms 80 bridge contacts 83 thereby energizing the magnet 4-9.

It is obvious that when the magnet 39 is energized, it attracts its armature and the circuit of motor 30 is closed at and said motor is started operating the pump 8; simultaneously with the starting of pump 8, the 'alve 26 is opened and the atmosphere is admitted beneath the piston '18 causing said piston to be quickly raised to its highest point, thus opening the valve 20 so thatair then supplied to pump 8 through the ports 17 and 1(5 and conduit 12. The current of air thus established in the transmission tube 1, drives the carrier "from the central station A to the sub station B. The valve 26 is only momentarily opened, and as soon as the piston 18 reaches its highest point, the valve 26 is closed again, and the piston gradually descends by gravity to the lower part of the cylinder 13 by means of the exhausting ot' the air from under said piston, through by-pass 23 and conduit 12. As the piston 18 reaches its lowest position, the collar 21 engages a latch 96 pivotally mounted on a movable member 97 of the switch 22, and opens said switch, thereby breaking the circuit of magnet 3-59 whose armature :t'alls away from, contacts 3:), thus breaking the circuit of motor 30, and stopping the pump 8. The descent of the piston 18 regulated by the adjustable valve 24: permitting a sullicient interval of time to ela 'ise before operating the switch 22 and stopping the motor 30 for the proper transmission and delivery of the carrier at the sub station B. The purpose of the pivoted latch 90 is to prevent the collar 21 from operating the. switch 22 during the ascent of said collar and to momentarily operate to open. said switch in its descent, the said switch closing automatically by gravity after the collar 21 passes below the latch 96. To operate the valve 26 as described, a magnet 98 is provided cooperating with the armature 27, on lever 27 and the circuit 99 of this magnet includes two normally disconnected contacts 100 which are bridged by the lever 58 when said lever is swung to the right as described. It is intended that orator to the right to the extreme of its movement, :it shall be immediately released and returned autinnatically by the spring (37) to its normal position breaking the circuit 9!), deiinergizing the magnet 98 and closing the valve 26 by means of the spring 29.

In sending a carrier from sub-station B to central station A, the operator at station l; swings the lever 78 to the left and the impulse of air through the pipe 7% shifts the diaphragm 72 and stem to the right, thus closing the switch 68, and energizing magnet 57. The member 50 is now swung to the right opening valve 11. and closing the circuit of magnet 4L9 through arms 80 bridging mntacts 8?). The resulting movement of the armature of magnet 49 closes the circuit of motor 40 at- 45 and said motor and pump 9 are started into action.

While the carrier is in transit from station It to station A, the prcssm'e between the carrier and the pump 9 is below atmospheric and therefore the diaphragm ()5 will be held in the position indicated by dotted lines at :1: (l ig. 4-) owing to the ports '101 provided in the chamber (5 1- admittiug the atmosphere to that side of the diaphragm, the opposite side of said diaphragm being in communication with the supply pipe 4 through pipe cc. As soon as the carrier discharges From the transmission tube at station A, the pres sure in the pipes 7 and l. and in the transmission tube '1, returns practically to atmospheric, and the resiliency of the diaphragm (l5 acting through stem (30 and link 61, returns the member 50 to its normal intermediate position. As has been heretofore described, the lever 58 is free of the stem (50 except for the pin (32, the lost motion between pin (32 and lever pern'iitting the stem (i0 to move imlependcntly oi the lever 58 to the left (Fig. l) and to remain there with the diaphragn'l ($5 in dotted line position indicated at a' while the pump 9 is in action. This connection between lever 58 and stem 60 also permits the lever 58 to be returned by spring (53 indepemlently ol stem (it), while pump 8 in action, and diaphragm (i5 is held in the dotted line position indicated at ;1 (Fig. l) by the air forced through pipe (in into chamber (34.

the pressure required in the transmis- (ion tube l to despatch a carrier from the central station A to the sub station 13 is greater than atmospheric pressure, it is necessary to hold the valve controlling the end ol the tube at station securely closed. li hcn a carrier is being despatchcd from sub station ii to central station A, the pressure in the tube '1 being less than atmosphere holds the valve closed. To serve this double object, I provide a latch 10? pivoted at 1.08 to the transmission tube 1 at central after the lever 58 has been swung by the opstation A. The tail of the latch 107 coopcrates with a cam 109 pivoted at 110, and which cam is adapted to be operated by a trip 11]. one end of which extends through a. slot in the transi'iiission tube 1 into the path of traveling carriers.

When a carrier is being despatched from sub station 13 to central station A, it strikes the trip 111, causing the cam 109 to swing the latch 107 out of engagement with. the arm 1,0 1 pivoted at 105 and to which is attached a valve 103, allowing said valve to be opened upon the impact of the carrier thereon. After the discharge of the carrier, the arm 104 and valve 103 are returned to normal position by a spring 106. It is necessary that the distance between the trip 111 and the valve 103 should be less than the length of the carrier, as this trip must be held depressed and the latch 107 released from the arm 104; at the time the forward end of the carrier strikes the valve 103.

In despatching a carrier from the central station A. to the sub-station B, the lower end of the latch 107 is pressed outward rein sing the arm 104 and opening the valve 103 when the carrier may be inserted into the transmission tube 1. As the trip 111 does not operate upon the latch 107 when the carrier is inserted into the tube for transmission from A to B, the latch is permitted to engage the arm 104 after the carrier has been inserted, which latch 107 holds the valve 103, securely closed against the high pressure necessary to drive the carrier in this direction to its destination.

Having thus described the nature of my invention and set forth a construction embodying the same, what I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In pneumatic despatch tube apparatus, a transit tube for the transmission of car riers in either direction, pressure and ex haust pumps communicating with the same end of the transit tube, independent valves normally closed controlling the communications between the pumps and the transit tube, valve operating mechanism common to both valves operating to open one or the other valve to establish communication between the transit tube and either pump, a motor for each pump, and means actuated by the valve-operating mechanism to set in motion the motor for the pump between which and the transit tube communication is established by said valve-operating mechanism.

In pneumatic despatch tube apparatus, a transit tube for the transmission of carriers in either direction, pressure and exhaust pumps con'nnunicating with the near end of the transit tube, independent valves normally closed controlling the communications between the pumps and the transit tube, valve-operating mechanism common to both valves operating to open one or the other valve to establish communication between the transit tube and either pump, a motor for each pump, means actuated by said valve-operating mechanism to set in motion the motor for the pump between which and the transit tube communication is established by said valve-operating mechanism, means controlled at the near end of the transit tube for actuating said valveoperating mechanism to open the valve controlling the communication between the transit tube and the pressure pump, and means controlled at the far end of the transit tube for actuating said valve-operating mechanism to open the valve controlling the communication between the transit tube and the exhaust pump.

3. In a pneumatic despatch tube system, a transit tube for the transmission of carriers, said tube having a plurality of terminals, one at least of which is normally open and adapted for the reception of carriers, air displacing means for exhausting air from said tube for transmitting said carriers, an air exhaust conduit between said air displacing means and the transit tube, a valve, adapted to throttle communication between said pump and transit tube, valve actuating means having a tendency to move into a determined position, said actuating means adapted to move said valve to a correspond ing position when permitted to respond to said tendency and adapted to be held out of said determined position only so long as at least a determined partial vacuum is maintained in a part of said conduit to one side of said valve, said valve being held open through the instrumentality of said actuating means normally substantially only so long as a carrier is in transit and the emergence of the carrier at its delivery terminal permitting the entrance of air at substantially atmospheric pressure to the said part of said conduit to substantially destroy the partial vacuum therein and effect the closure of said valve.

41-. In pneumatic despatch tube apparatus, a transit tube for the transmission of carriers, an exhaust pump communicating with the near end of the transit tube, a normally closed valve controlling the communication between the pump and the transit tube, an electric motor to drive said pump having a normally open switch in its circuit, an electro-magnet with a normally open circuit for closing the switch of the electric motor when said electro-magnet is energized, a pivoted lever operating to open said valve and to close the circuit through the electro-magnet, a second electroanagnet when energized for moving said lever to open the valve and to close the circuit of the first clectro-magnet, a normally open switch in the circuit of the second electro-magnet. a pneumatic motor for operating the switch to close the circuit through the second electro-magnet, and a pneumatic pump at the far end of the transit tube communicating with said pneumatic motor to operate the latter to close the switch in the circuit of the second electromagnet to energize the latter.

5. In a pneumatic despatch tube apparatus, a transit tube for the transmission of carriers, a pump in communication with said transit tube, a valve having a bias for its closed position, said valve controlling the communication between said pump and tube, mechanism for opening said valve, a valve controlling pneumatic device in communication with said transit tube and pump, said device including a wall adapted to be moved from a determined and normal position thereof to a second position, by the establishment of a diti'erence in pressure in said tube created by said pump, said wall adapted to maintain said valve open when in its said second position and having a tendency to resume its normal position to effect the reclosure of said valve upon the dis-establishment of said digtlerence in pressure.

(3. In a pneun'iatic despatch tube system, a transit tube for the transmission of carriers, said tube provided with terminals, one at least of which is provided with a normally closed valve, means for establishing a carrier propelling current of air in said tube, said means having provisions tending to dis-establish said air current, a pneumatic device in communication with a part of the system and having a portion thereof responsive to changes in pressure in said part, said portion of said pneumatic device having a tendency for a determined position but adapted to be held out of said position by a given pressure of air in said part oil the system, said device adapted to prevent the disestablishment of said air current by the provisions aforesaid so long as said given pressure continues.

7. In a pneumatic despatch tube system, a transit tube for the transmission of carriers, means for establishing a carrier propelling current of air in said tube, said means having provisions tending to disestablish said air current, a pneumatic device in communication with a part of the system and having a portion thereof responsive to changes in pressure in said part, said portion of said pneumatic device having a tendency for a determined position but adapted to be held out of said. position by a given pressure of air in said part of the system, said device adapted to prevent the dis-establishment of said air current by the provisions aforesaid so long as said given pressure continues and means including a timingmechanism, for eil'ecting an operative departure from said given pressure in said part of the system whereby to permit said portion to move into its said determined position.

8. In a pneumatic despatch tube system, a transit tube for the transmission of carriers, said tube provided with terminals, one at least of which is a despatchingterminal, means for establishing a carrier propelling current of air in said tube, said means having provisions tending to dis-establish said air current, a pneumatic device in communication with a part of the system and having a portion thereof responsive to changes in pressure in said part, said portion oil said pneumatic device having a tendency for a determined position but adapted to he held out of said position by a given pressure of air in said part of the system, said device adapted to prevent the dis-establishment of said air current by the provisions aforesaid so long as said given pressure continues, and means including a timing mechanism for effecting an operative departure from said given pressure, in "said part of the system, whereby to permit said portion to move into its said determined position, said timing mechanism adapted to be re-timed for each successive carrier transmitted from said despatching terminal.

t). In pneumatic despatch tube apparatus, a transit tube for the transmission of carriers, means for supplying compressed air to said tube or for exhausting air therefrom in accordance with the direction of travel of a carrier therethrough, said means including two conduits, one for delivering compressed air to said tube and one for conveying away air exhausted therefrom, to- .'.;'ether with mechanism for switching one or the other of said conduits into communication with said tube, and means for maintaining operative said mechanism a'l'ter being set for switching air through the conduit selected, said last mentioned means comprising a pneumatic device in communication with said tube and. having a wall thereof displaceable from a position which it normally occupies by the estal'ilishment of a ditlerence in pressure in said tube, said wall having operative connections with a part of said switching Il'lBGlHtIllSll'l adapted to hold said part substantially in the position into which it was moved when said mechanism was set.

10. In a pneumatic despatch tube system, tubular means for guiding carriers in transit between two stations, means for transmitting carriers from one of said stations to another by air above atmospheric pressure and for transmitting carriers from said other station to that first mentioned by air at substantially atmospheric pressure, timing mechanism for limiting the flow of air transmitting carriers one way, and means, operable by a change in pressure of the air in a. part at least of said tubular means, caused by the passage of a carrier past a determined point in said means, for limiting the flow of air transmitting carriers in an opposite direction.

11. In a pneumatic despatch tube system, tubular means for guiding carriers in transit between two stations, means for transmitting carriers from one of said stations to another by air above atmospheric pressure and for transmitting carriers from said other station to thatfirst mentioned by air at substantially atmospheric pressure, timing mechanism for limiting the flow of air transmitting carriers one way, and means, operable by a change in pressure of the air in a part at least of said tubular means, caused bythe passage of a carrier past a determined point in said means, for limiting the flow of air transmitting carriers in an opposite direction, a part of said last mentioned means acting to maintain the flow or air transmitting carriers in the first mentioned direction.

In a pneumatic despatch tube system, tubular means ;tor guiding carriers in transit between two stations, means for transmitting carriers from one of said stations to another by air above atmospheric pressure and for transmitting carriers from said other station to that first mentioned by air at substantially atmospheric pressure, apart of said means having a tendency for a position in which it is adapted to render said means ii-ioperative, and a pneumatic device in communication with said tubular means tor holding said part out of said position during the continuance of carrier transmitting conditions in either direction in said system. 13. In a pneumatic despatch tube system, tubular means for guiding carriers in transit between two stations, means for transmitting carriers from one of said stationsto another by air above atmospheric pressure land for transmitting carriers from said other station to that first mentioned :by air at substantially atmospheric pressure, a part of said means having ;a tendency for a position in which it is adapted to render said means inoperative, a pneumatic device in communication with said tubular means for holding said part out of said position during :the continuance of carrier transmitting conditions in either direction in said system, and means, including a timing mechanism, for automatically dis-establishing said conditions, whereby to effect the release of said part.

14:. In a pneumatic despatch tube system, tubular means vfor guiding carriers in transit between two stations, means tortransmitting carrier-s firom one of said stations to another by air above atmospheric pressure and for transmitting carriers from saidother station to that first mentioned by air atsubstantially atmospheric pressure, a part of said means having a tendency for a position in which it is adapted to render said means inoperative, and a pneumatic device in communication with said tubular means for holding said part out of said position during the continuance of carrier transmitting conditions in either direction in said system, aid system having provisions "for efi ecting the release of said part after the transmission of a carrier.

15. In a pneumatic despatch tube system, tubular means for guiding carriers in tran sit between two stations, means for transmitting carriers from one of said stations to another by air above atmospheric pressure and tor transmitting carriers from said other station to that first mentioned by air at substantially atmospheric pressure, a part of said means having a tendency for a position in which it is adapted to render said means inoperative, and a pneumatic device in, communication with said tubular means for holding said part out of said position during the continuance of carrier transmitting con di-tions in either direction in said system, said system having provisions, including a timing mechanism, for etl ecting the release of said pant after the transmission oi": a carrier.

16. In a pneumatic despatch tube system, a transit tube for the transmission of car riers, said tube provided with terminals one at least of which has a closure, means coacting with said closure for establishing a carrier propelling current'ot air in said tube, said means having a partthereof normally tending to dis-establish said air current, a pneumatic device in communication with said tube and having a portion thereof responsive to changes in pressure in the air therein and adapted to be held in one determined position by a given pressure of air in said tube, said device adapted to restrain the part aforesaid against movement by its said tendency so long as said given pressure continues.

17. In a pneumatic despatch tube system, a single tube adapted for the transmission of carriers in. either direction therethrough, a normally non-reversible pump adapted to be placed in communication with said tube for transmitting carriers one way by compressed air, a second normally non-reversible pump adapted to be placed in communication with said tube for transmitting can riers therethrough in the opposite direction. means for placing one or the other of said pinnps in communication with said tubes in accordance with the requirements of service conditions in the system, and means for starting one or the other of said pumps in accordance with the communications established by said last mentioned means, said system having provisions for stopping the pump which is in operation and dis-estalr lishing communication therewith after the transmission of the carrier through said tube.

18. In a pneumatic despatch tube system, having a plurality of stations, means relatively remote from one of saidrstations for establishing a carrier propelling current of air flowing from said station toward another of said stations said last mentioned means including an electric circuit having therein a switch, a source of electric current in circuit with said switch and an electro-magnetic device, means controlled by said. device for creating a difference in pressure in the air in said tube at the respective stations aforesaid, and pneumatic means for rendering operative said first mentioned means, said pneumatic means including an auxiliary tube for transmitting air under pressure from said first mentioned station substantially to said switch, a pneumatic dos vice in communication with said last men tioned tube for actuating said switch and means at said first mentioned station for creating a difference in pressure in said aux iliary tube.

19. In a pneumatic despatch tube system, a transit tube for the transmission of carriers, said tube having a plurality of terminals, one at least of which is normally open and adapted for the reception of car riers, air displacing means for exhausting air from said tube for transmitting said carriers, an air exhaust conduit between said air displacing means and the transit tube,

a valve, adapted to throttle communication between said pump and transit tube, valve actuating means having a tendency to move into a determined position, said actuating means adapted to move said valve to a corresponding position when permitted to re spond to said tendency and adapted to be held out of said determined position only so long as at least a determined partial vacuum is maintained in a part of said conduit to that side of said valve which is the more remote from said pump, said valve being held open through the instrumentality of said actuating means normally substantially only so long as a carrier is in transit and the emergence of the carrier at its delivery terminal permitting the ent'ance of air at substantially atmospheric pressure to the said part of said conduit to substantially destroy the partial vacuum therein.

20. In a pneumatic despatch tube system, a transit tube for the transmission of can riers, said tube having a plurality of terminals, one at least of which is normally open and. adapted for the reception of car riers. air displacing means for exhausting air from said tube for transmitting said carriers, an air exhaust conduit between said air displacing means and the transit tube,

a valve, adapted to throttle eomnmnication between said pump and transit tube, rcsili ent valve actuating means having a tendency to move into a determined position, said means adapted to move said valve to a corresponding position when permitted to respond to said tendency and adapted to be held out of said determined position only so long as at least a determined partial vacuum is maintained in a determined part of said conduit, said valve being held open through the instrun'ientality of said means normally substantially only so long as a carrier is in transit and the emergence of the carrier at its delivery terminal permitting the entrance of sullicient air through said open terminal to said determined part of said conduit to destroy said partial vacuum therein;

21. In apneumatic despatch tube system, a transit tube normally open to the atmosphere, a carrier, air displacing means for creating a carrier transmitting current of air through said tube, a valve between said tube and said air displacing means adapted to control said current of air, saidsystem having parts disposed in adjacency to said valve and adapted to co'act therewith to permit a free flow of said air current only so long as there exists a determined relationship between the pressure in said transit tube and that in the side of said air displacing means which is connected to said tube, the emergence of the carrier from the tube destroying said determined relationship.

22. In a pneumatic despatch tube system, a transit tube normally open to tln atmosphere, a carrier, air displacing means for creating a carrier transmitting current of. air through said tube, an element between said tube and said air displacing means adapted to directly control said current o't air, said system also having auxiliary elements disposed inadjacency to said first mentioned element and adapted to co-act therewith to permit a free flow of said air current only so long as there exists a determined relationship between the pressure in said transit tube and that in the side of said air displacing means which is connected to said tube, the emergence of the carrier from the tube destroying said determined relationship, one of said elements being resilient and tending thereby to move into a determined position, said resilient one of said elements being adapted to be held out of said positionby air pressure and to move to its said determined position when pressure upon opposite sides thereof is substantially equalized.

23. In a penumatic despatch tube system, a transit tube normally open to the atmosphere, a carrier adapted for transmission through said tube, means connected with said tube for creating a carrier propelling current of ,air therethrough, a valve for con.- trolling ,cemm-unieation between said tube and said means, said system having parts to co-aet with said Value to permit a free flow of said air current only so long as there exists a determined relationship between the pressulie in the transit tube and that in the side of said means which is in communication with the tube, the emergence of said carrier from the tube substantially destroyingsaid determined relationship,

In ,a pneumatic despatch tube system, atransit tube normally open to the atmosphere, a earrier adapted tor transmission thronghsaid tube, a pump for exhausting air from said tube to propel said carrier therethro-ugh, said tube havinga terminal through which said carrier may be inserted, and said system, further, having means, con.- trolled by the current of ;air which enters the normally open tube behind said carrier, to normally throttle eemmunieation between said tube and pump when said carrier has passed a determined point in said tube to permit access of said air to said means.

25. In ,a pneumatic despatch tube system, a transit tube normally open to the atmosphere, ,a carrier adapted tor transmission through said tube, means for creating a carrier transmitting flow of air through said tube, said tube having a terminal through which said earrier may be inserted, and said system, further, haying fluid pressure .controlled means operative upon the passage of the carrier past a determined point in said tube, to throttle communication between said tube and said first mentioned means,

In testimeny whereof, I have signed my am t thi spe itic on i th p e n at two subscribing witnesses, this twenty-see- 4 0nd day of November A. D. 1906.

M S '1- eowLEY. lVitness-es:

@- R ERT LIB -Y, M 11. H. :KNOWLKEON.

Copies of this patent may he obtained for five cents each, by addressing the fiommissiener of Batents, Washington, D. .6. 

